ASK SAIL

May 15, 20184 minutes

WHY DO DIESELS LIKE HARD WORK?

Q: I keep hearing that diesel engines “like” to be worked hard. I also understand that it can be a problem only using an auxiliary for brief periods, like just going in and out of a marina, as opposed to prolonged periods. Why is this? How much should a diesel be run to keep it in good shape, and what can a daysailer like me do to make sure I get in the right amount of run time?

— Scott Henderson, Houston, TX

NIGEL CALDER REPLIES

When a diesel engine is first warmed up, it is considerably less efficient than when